The rotating parts of the wind turbine including the blades and blade assembly.

Detremines the torque needed to for a desired angular acceleration about a rotational axis.

The rotating part of an electric motor.

Rotational energy or angular kinetic energy is kinetic energy due to the rotation of an object and is part of its total kinetic energy.

A rotary (rotatory) transformer is a specialized transformer used to couple electrical signals between two parts that rotate in relation to each other.

A rotary table is a mechanical device on a drilling rig that provides clockwise (as viewed from above) rotational force to the drill string to facilitate the process of drilling a borehole.

Rotary thermal wheels are a mechanical means of heat recovery.

Pumps that move fluid using a rotating mechanism that creates a vacuum that captures and draws in the liquid.

An internal combustion engine, usually designed with an odd number of cylinders per row in a radial configuration, in which the crankshaft remained stationary in operation, with the entire crankcase and its attached cylinders rotating around it as a unit.

A rotary converter is a type of electrical machine which acts as a mechanical rectifier, inverter or frequency converter.

A rooftop photovoltaic power station, or rooftop PV system, is a photovoltaic (PV) system that has its electricity-generating solar panels mounted on the rooftop of a residential or commercial building or structure.

A rolling blackout is an intentionally-engineered electrical power shutdown in which electricity delivery is stopped for non-overlapping periods of time over different parts of the distribution region.

Rock-fill dams are embankments of compacted free-draining granular earth with an impervious zone.

Risk management is the identification, evaluation, and prioritization of risks (defined in ISO 31000 as the effect of uncertainty on objectives) followed by coordinated and economical application of resources to minimize, monitor, and control the probability or impact of unfortunate events or to maximize the realization of opportunities.

A risk assessment determines possible mishaps, their likelihood and consequences, and the tolerances for such events.

Risk analysis is a technique used to identify and assess factors that may jeopardize the success of a project or achieving a goal.

The international standard definition of risk for common understanding in different applications is “effect of uncertainty on objectives”. Risk is the probability that exposure to a hazard will lead to a negative consequence.

Ripple control is a common form of load control, which involves superimposing a higher-frequency signal onto the standard 50–60 Hz of the main power signal. When receiver devices attached to non-essential residential or industrial loads receive this signal, they shut down the load until the signal is disabled or another frequency signal is received.

A ring main unit is a factory assembled, metal enclosed set of switchgear used at the load connection points of a ring-type distribution network.

In electricity supply design, a ring final circuit or ring circuit is an electrical wiring technique developed and primarily used in the United Kingdom, and to a lesser extent in Ireland and Hong Kong.